Some state and local gun-control measures already have died over the past 41/2 years, done in by the high court's 2008 ruling that recognized expansive constitutional protections for firearm ownership. Similar Second Amendment restraints will limit the ambitions of the Obama gun task force and its Capitol Hill counterparts.

"The Supreme Court has decided that the amendment confers a right to bear arms for self-defense, which is as important outside the home as inside," Judge Richard Posner of the 7th U.S. Circuit Court of Appeals noted in a ruling last week.

Some additional gun restrictions, however, certainly will survive legal challenge. The Supreme Court has said that "laws imposing conditions and qualifications" on firearms sales may be permitted. This might allow, for instance, more background-check requirements. The court further indicated in 2008 that "an important limitation on the right to keep and carry arms" extends to "dangerous and unusual weapons."

That might include military firearms such as the M16 assault rifle, which the Supreme Court specifically cited. Adam Lanza, who killed 20 children and six women last Friday at Sandy Hook Elementary School in Newtown, Conn., used a Bushmaster AR-15-style rifle, a civilian version of the M16.

The Supreme Court's 2008 decision, however, has confining power. Posner's ruling last week underscored that. His opinion struck down an Illinois law that prohibited most individuals from carrying firearms in public. An outspoken conservative intellectual, Posner previously had criticized Justice Antonin Scalia's reasoning in the high court's decision. Like it or not, though, judges now must abide by it.

Or, as Posner put it, "the Supreme Court's interpretation of the Second Amendment . compels us" to strike down the Illinois law.

"If the government is going to intrude on a fundamental right, they are going to have to have a compelling governmental interest and the law will have to be fitted to achieve those ends," San Jose, Calif., attorney Donald Kilmer said in an interview. He represents the Calguns Foundation, a California advocacy group for firearms owners, in lawsuits challenging gun laws.

Eugene Volokh, a professor at UCLA Law School who's written a lot about the Second Amendment, said in an interview Wednesday that he was skeptical about the effectiveness of any new federal gun-control measure, though he thinks a number of federal proposals could survive constitutional challenge. But with California lawmakers now considering proposals such as a first-of-its-kind requirement to obtain ammunition licenses, he added that some politicians might intrude too far into protected territory.

"I'm more concerned at the state level," Volokh said.

Other laws, too, have fallen in the wake of the Supreme Court's 5-4 ruling in the landmark gun rights case known as District of Columbia v. Heller. The ruling, which struck down Washington's sweeping ban on handguns, applied to federal jurisdictions. A subsequent Supreme Court ruling in 2010 extended the Second Amendment reasoning to limit what states and localities can do, a constitutional step called incorporation.